The present invention relates to a method of processing a specimen using a plasma etching process, an apparatus therefor, and a method of manufacture of a magnetic head using the same.
A specimen, such as a substrate of a semiconductor device and the like, is subjected to etching processing, for example, using a chemical solution or plasma. In such etching processing of the specimen, it is necessary to pay sufficient attention to the occurrence of corrosion in the specimen after the etching processing.
As such anti-corrosion technology for the specimen after the etching processing, there is a known technique as disclosed, for example, in JP-A Laid-Open No. 59-186326, wherein any chlorine compound, which is a corrosive substance remaining in resist films and the like is removed by ashing processing of the resist films using a plasma in a plasma process chamber which is in communication with an etching chamber that is maintained in a vacuum. Further it is known that, by heating the specimen after etching at 200xc2x0 C. or more, evaporation of the chlorine compound, which is a corrosive substance remaining in the specimen, is promoted, thereby preventing the occurrence of corrosion of the specimen after etching. Further, there is also a known process, as disclosed in JP-A Laid-Open No. 61-133388, wherein an object to be treated, such as a specimen which has been etched, is transferred from the etching chamber to a heat treatment chamber in which the object to be treated is dried by blowing heated air over it, then it is taken out of the heat treatment chamber to be rinsed with water and then dried, thereby preventing the corrosion of the object after its etch processing due to reaction with the atmosphere.
JP-A Laid-Open No. 2-224233 discloses a method for processing specimens, which method is comprised of: a first step of etching a specimen, in the form of a lamination which contains different metals each having a different ionization characteristic from the other, using a first gas plasma via a resist mask formed on the lamination specimen in a first processing chamber; a second step of removing the resist mask and residual corrosion substances deposited on a side wall of the laminated specimen containing metals having different ionization characteristics from each other, which are formed in the first step, by processing the specimen in a second processing chamber using a second gas plasma formed in a different gas atmosphere from that of the first gas plasma; and a third step of removing a remaining portion of the residual corrosive substances deposited on the side wall of the laminated specimen which could not have been removed by the second step, by causing surfaces of the specimen which are exposed by the first and the second steps to come into contact with at least one liquid. According to this method, in the first step, the specimen which is prepared by laminating an Al alloy film and a TiW or TiN film is etched using a gas plasma which contains chlorine via the resist mask under decompression; in the second step, the specimen is subjected to an ashing process using a gas plasma which contains oxygen; and in the third step, the specimen is rinsed with water, and wherein in order to remove the residual corrosive substances remaining after the first step, the third step is comprised of at least one of the steps of: (a) rinsing in water; (b) further rinsing in water after rinsing in an alkaline liquid; (c) still further rinsing in water after rinsing in an acidic liquid, and (d) rinsing in water after rinsing in a fluoro-acid solution.
A method of etching a material used for magnetic poles in a thin film magnetic head, magnetic sensor and the like, which contains Fe, is disclosed in JP-A Laid-Open No. 4-107281. In this publication, a method of etching alloys which contain Fe, in particular, Fexe2x80x94Sixe2x80x94Al alloy, formed on a surface of a specimen is disclosed, which method is comprised of: a step of etching a specimen which is heated in a vacuum at a temperature which is above 250xc2x0 C. and below its melting point in an atmosphere of chlorine gas by a reactive ion milling method; a step of post-processing the specimen which is maintained at a high temperature above 250xc2x0 C. by applying a chlorine ion shower thereto in order to allow for etching residuals remaining on the surface of the specimen to completely react with the chlorine gas; and a step of pure water processing for dissolving and removing etching products which are produced in the post processing step by submerging the specimen in pure water, wherein the above-mentioned steps are executed consecutively in the sequence described above.
Further, JP-A Laid-Open No. 7-93293 discloses a method which is comprised of the steps of: etching a specimen formed of a lamination of wired material which contains aluminum; then removing halogen compounds and resist compounds at the same time.
A problem associated with the technique indicated in JP-A Laid-open No. 4-107281 resides in the fact that, in a case where pure Fe which is 3 xcexcm thick is etched by argon ion milling for the manufacture of a magnetic head, because the etching rate is approximately 150 A/min, it takes 200 min. This is because the etching rate is controlled by the number of incident ions. In order to improve the etching rate, it is suggested in JP-A Laid-open No. 4-107281 that by heating a specimen above 250xc2x0 C., and by applying reactive ion milling in a chlorine gas atmosphere, the etching rate can be improved approximately to 1000 A/min. However, there is a problem in that some types of specimens cannot withstand a temperature above 250xc2x0 C. depending on the materials, thereby preventing application of the above-mentioned method. In particular, there arises a problem when etching a laminated film which contains a ferromagnetic material of NiFe alloy for use in the manufacture of a magnetic head in that, if the temperature of its specimen rises above 230xc2x0 C., the magnetic property of its NiFe film is deteriorated, and even when its temperature drops to the normal temperature, its original magnetic property cannot be recovered, thereby rendering it useless.
Still further, an anti-corrosion process is proposed for preventing corrosion which occurs in a specimen which is left after application of reactive ion milling in JP-A Laid-Open No. 4-107281, comprising: a post-treatment process for applying a chlorine ion shower onto the specimen which is heated at a temperature above 250xc2x0 C.; and a pure water immersion process for immersing the specimen in pure water, wherein the above-mentioned processes are executed sequentially in this order. However, there is a problem in that the temperature of the specimen rises above 250xc2x0 C., and a complicated sequence of anti-corrosion processing, including the ion shower and then the pure water immersion processes, is required, thereby increasing the cost of manufacture.
The above-mentioned complicated sequences for corrosion prevention processes are considered to be due to the fact that the specimen target, which is a Fexe2x80x94Sixe2x80x94Al alloy and contains two different metals which differ greatly in ionization characteristics from each other, as indicated in JP-A Laid-open No. 2-224233, has a high corrosiveness.
An object of the present invention is to provide a method of processing a specimen for corrosion prevention thereof, an apparatus therefor and a method of manufacture of a magnetic head using the same, which allows for etching of a specimen, such as a laminated film containing NiFe alloy, at a high rate and at a temperature which is low enough not to destroy the device, in a simple manner and at a low cost.
A method for accomplishing the object of the invention is comprised of the steps of: etching a specimen, for example, a magnetic pole for a magnetic head, which is formed using NiFe alloy, after plasma processing the same using a relatively high density plasma source; and subjecting the specimen to a post-plasma processing for corrosion prevention immediately after the etching, using a gas plasma which contains H2O or methanol, under a pressure at 50 Pa or above, at a temperature of the specimen below 200xc2x0 C.
Here, the relatively high density plasma source refers to an induction-coupled type plasma apparatus, helicon type plasma apparatus, two-frequency excitation parallel plane type plasma apparatus or microwave type plasma apparatus, which can irradiate a specimen with a plasma of a saturated ion current density of approximately 1-10 mA/cm2. Compared to the conventional low density plasma source, such as ion milling and parallel plane types, this has a plasma density as high as 10 to 100 times greater. Further, because another high frequency power source is provided to a specimen stage in addition to a high frequency power source for plasma production, ion energy to be input to the specimen can be controlled independently. If this plasma source of the invention is used, because it ensures that a sufficient number of incidence ions will be produced, it becomes possible to obtain a high etching rate even if the energy of the ions of incidence is set at 50-500 eV, or from xc2xd to {fraction (1/10)} of the milling method, and at a lower temperature of the specimen. For example, an etching rate of 100 nm/min can be realized at 40xc2x0 C. of the specimen and at 300 eV of ion energy. Also, there is a merit if the temperature of the specimen is held in a range from 40 to 60xc2x0 C. that the design and construction of its specimen""s stage is simplified thereby contributing to a reduction of the cost of manufacture.
Further, in the high density plasma processing of the invention, because of a shallowness of penetration of chlorine ions bombarded into an NiFe alloy layer due to a low bombardment ion energy, and because Ni and Fe are the same type of metals having the same ionization characteristics, thereby preventing the above-mentioned corrosion mechanism due to the different ionization characteristics from occurring, corrosion prevention of the specimen becomes possible by removing residual chlorine compounds deposited on the surface of the specimen after etching thereof by exposing the same to a gas plasma containing H2O or methanol under a pressure of 50 Pa or more, and at a temperature of the specimen below 200xc2x0 C., and thereby providing for a simpler and lower cost corrosion prevention method and an apparatus therefor.
Also, the lamination film used for manufacture of the magnetic head includes, in addition to NiFe alloy film, oxide film layers such as alumina, oxide silicon film and the like, and/or various other layers such as a photo-resist layer and the like, which are to be processed by etching in a plasma. However, in the etching thereof, there arises a case where its NiFe alloy layer is exposed from its under-layer, or where its oxide film layer is etched using the NiFe alloy layer itself as a mask. During such processes, the NiFe alloy layer is exposed to a chlorine or fluorine plasma atmosphere. Therefore, a post-etching corrosion prevention treatment is required. For these etching processes, the corrosion prevention treatment by exposing the specimen to a gas plasma containing H2O or methanol according the invention can be applied as well.
The method and the apparatus to be provided according to the invention will be more specifically described in the following.
A method of processing a specimen according to the invention is comprised of: a first step of etching a laminated film formed on a substrate, which contains at least one layer comprising a NiFe alloy or NiFeCo alloy by applying a gas plasma which contains chlorine, at a temperature of the specimen below 200xc2x0 C. in an etching chamber; and a second step of plasma post-processing for removing residual chlorine compounds deposited on the lamination layer by applying a gas plasma which contains H2O or methanol on the lamination films exposed by the first step, under a pressure at 50 Pa or more and at a temperature of the specimen below 200xc2x0 C.
The present invention further provides for a method of processing the specimen, wherein its gas plasma is produced by at least one or more in combination selected from the group consisting of Cl2, BCl3, Ar and O2.
The invention provides for a method of processing the specimen, wherein the other lamination layer is comprised of at least one of (A) a photo-resist layer, (B) an alumina (Al2O3) layer, (C) a silicon oxide layer, (D) a Cu layer, (E) a Ta layer, and (F) a Cr layer, which are to be etched by a gas plasma in an etching chamber.
According to another aspect of the invention, a method of etching the specimen in an etching chamber is provided, which specimen is comprised of a sintered substrate made of Al2O3 and TiC, and a layer of NiFe alloy formed on the substrate.
According to still another aspect of the invention, a method of manufacture of a magnetic head having an upper magnetic pole and a lower magnetic pole disposed opposite to the upper magnetic pole is provided, which is comprised of the steps of: forming a lamination film which is comprised of an upper photo-resist layer, a hard mask of SiO2 or alumina, a lower photo-resist layer, and a seed layer of NiFe alloy; plasma-etching the hard mask layer using the upper photo-resist layer as a mask; forming a deep groove by plasma-etching in the lower photo-resist layer using the hard mask layer as a mask with a gas which contains chlorine so as to expose the seed layer in the bottom of the deep groove; removing a residual chlorine compound which is deposited on an exposed portion of the seed layer by a plasma post-treatment using a gas plasma which contains H2O or methanol; then, embedding a NiFe alloy into the deep groove to make contact with the seed layer.
According to a still further aspect of the invention, a method of manufacture of a magnetic head having an upper magnetic pole and a lower magnetic pole disposed opposite to the upper magnetic pole is provided, which is comprised of the steps of: forming a lamination film which is comprised of a seed layer made of NiFe alloy, an upper magnetic pole made of NiFe alloy which is in contact with the seed layer, a gap layer of an oxide film in close contact with the seed layer, and a shield layer made of NiFe alloy in close contact with the gap layer; plasma-etching the seed layer using the upper magnetic pole as a mask with a gas which contains chlorine; then, removing a residual chlorine compound by a plasma post-treatment with a gas plasma which contains H2O or methanol.
According to a still further aspect of the invention, a method of manufacture of a magnetic head having an upper magnetic pole and a lower magnetic pole disposed opposite to the upper magnetic pole is provided, which is comprised of the steps of forming a lamination f film which is comprised of a seed layer made of NiFe alloy, an upper magnetic pole made of NiFe alloy which is in contact with the seed layer, a gap layer of an oxide film in close contact with the seed layer, and a shield layer made of NiFe alloy in close contact with the gap layer; etching the seed layer; plasma-etching the gap layer using the upper magnetic pole as its mask with a gas compound which contains chlorine or fluorine, then; removing a residual chlorine compound by a gas plasma which contains H2O or methanol.
According to a still further aspect of the invention, a method of manufacture of a magnetic head having an upper magnetic pole and a lower magnetic pole disposed opposite to the upper magnetic pole is provided, which is comprised of the steps of: forming a lamination f film which is comprised of a seed layer made of NiFe alloy, an upper magnetic pole made of NiFe alloy which is in contact with the seed layer, a gap layer of an oxide f film in close contact with the seed layer, and a shield layer made of NiFe alloy in close contact with the gap layer; etching the seed layer; etching the gap layer; trim-etching the shield layer using the upper magnetic pole as its mask by plasma treatment with a gas compound which contains chlorine, then; removing a residual chlorine compound by a plasma post-treatment with a gas plasma which contains H2O or methanol.
According to still another aspect of the invention, a method of manufacture of a magnetic head having an upper magnetic pole and a lower magnetic pole disposed opposite to the upper magnetic pole is provided, which is comprised of the steps of: forming a lamination f film which is comprised of a seed layer made of NiFe alloy, an upper magnetic pole made of NiFe alloy which is in contact with the seed layer, a gap layer of an oxide film in close contact with the seed layer, and a shield layer made of NiFe alloy in close contact with the gap layer; plasma-etching each of the seed layer, the gap layer and the shield layer exclusively in each vertical direction thereof using the upper magnetic pole as a mask; and removing a residual chlorine compound deposited on a processed surface by a plasma post-treatment with a gas plasma which contains H2O or methanol.
According to still another aspect of the invention, a method of manufacture of a magnetic head is provided, wherein the gap layer is processed with a gas plasma which contains chlorine or fluorine, and the seed and the shield layers are processed with a gas plasma which contains chlorine and argon gas.
According to one aspect of the invention, an apparatus for etching a specimen which is laminated on a substrate is provided, which is comprised of: an etching processing device, which is supplied with a gas for forming a plasma, and generates a gas plasma, for etching a laminated film which includes at least one layer made of NiFe alloy or NiFeCo alloy formed on a substrate by a gas plasma which contains chlorine at a temperature below 200xc2x0 C. of the specimen in an etching chamber; and a plasma post-treatment device for removing a residual chlorine compound deposited on the layers made of NiFe alloys exposed by the etching processing with a gas plasma which contains H2O or methanol, under pressure below 50 Pa and at a temperature below 200xc2x0 C.
According to another aspect of the invention, an apparatus for processing a specimen is provided, which is comprised of: an atmospheric loader; a vacuum transport chamber including a vacuum transport robot provided therein; and unload and load lock chambers which connect between the atmospheric loader and the vacuum transport chamber, and transfer the specimen therebetween, wherein the vacuum transport chamber is connected to the etching chamber of the etching processing device, and the atmospheric loader is connected to the plasma post-treatment chamber of the plasma post-treatment device.
Further, the etching chamber according to the invention is provided with a plurality of processing devices for processing the specimen.